Lymph nodes are small, bean-shaped glands that are part of the body’s immune system. They filter lymph fluid, a clear, watery substance that circulates throughout the body, collecting waste products and foreign particles. These nodes contain immune cells, such as lymphocytes, which identify and fight off infections and abnormal cells, including cancer cells. Lymph nodes are found in various locations throughout the body, including the neck, armpits, chest, groin, and abdomen, with hundreds distributed across the lymphatic system. Stomach cancer, also known as gastric cancer, originates in the cells lining the stomach.
How Cancer Spreads to Lymph Nodes
Cancer cells can detach from the primary tumor in the stomach and spread through a process called metastasis. The lymphatic system provides a common pathway for this spread. Cancer cells can enter the small lymphatic vessels that surround the stomach.
Once inside these vessels, cancer cells travel with the lymph fluid to nearby regional lymph nodes. These nodes act as collection points. When cancer cells reach a lymph node, they can become trapped and grow, forming new tumors. The presence of cancer cells in lymph nodes indicates that the disease has progressed beyond the stomach, signifying a more advanced stage.
Detecting Lymph Node Involvement
Detecting stomach cancer spread to lymph nodes is crucial for diagnosis and staging. Doctors use several methods. Imaging techniques like computed tomography (CT) and positron emission tomography (PET) scans visualize lymph nodes. These scans can reveal enlarged lymph nodes, which may suggest cancer, though enlargement can also be due to infection or inflammation.
Endoscopic ultrasound (EUS) provides detailed images of the stomach wall and surrounding lymph nodes, involving a thin, flexible tube with an ultrasound probe inserted into the stomach. To confirm cancer, a biopsy is performed. This can involve a fine needle aspiration (FNA) to collect cells from a suspicious lymph node, or a surgical biopsy where a portion or the entire node is removed for examination. The number and specific location of cancerous lymph nodes are crucial for determining the cancer’s stage, particularly within the TNM (Tumor, Node, Metastasis) staging system, where “N” refers to nodal involvement.
Treatment Based on Lymph Node Status
Lymph node involvement directly influences stomach cancer treatment. During surgery to remove the stomach tumor, known as a gastrectomy, lymphadenectomy is performed. This involves the surgical removal of nearby lymph nodes to eliminate cancerous nodes and provide accurate information for cancer staging. The extent of lymph node removal depends on the stage and location of the primary tumor, with more advanced cases often requiring a broader dissection of regional lymph nodes.
Lymph node involvement also dictates the need for additional therapies. Chemotherapy, which uses drugs to kill cancer cells, may be administered before surgery (neoadjuvant therapy) to shrink tumors, or after surgery (adjuvant therapy) to target remaining cancer cells and reduce recurrence risk. Radiation therapy, which uses high-energy rays to destroy cancer cells, may also be considered with chemotherapy. These treatments are selected based on the cancer’s characteristics and the extent of lymph node involvement, aiming to improve outcomes and prevent disease spread.
Prognosis and Lymph Node Status
Lymph node status is a primary factor in determining the prognosis for stomach cancer. The presence of cancer cells in the lymph nodes generally indicates a less favorable prognosis than in cases where lymph nodes are unaffected. The number of involved lymph nodes and their specific locations are strong indicators of disease aggressiveness and recurrence likelihood. Patients with more lymph nodes containing cancer typically face a higher risk of recurrence and a lower survival rate. Other elements also contribute to the overall prognosis, including the primary tumor’s characteristics (size and invasion depth), patient’s general health, and response to treatment.